1. Field of the Invention
The present invention relates to a conveying device, an image forming apparatus, and a program.
2. Description of the Related Art
Conventionally, a roller, a belt, or the like, which is made of rubber, polyurethane, or the like, is used on a conveying path on which a recording medium such as a sheet is conveyed in an automatic document feeder (ADF) or the like of a printer or a scanner. With increasing the number of sheets conveyed, the surface of the roller or the like becomes worn, and this may cause the sheet to slip. In addition, paper dust and a foreign substance, etc. attached to the surface of the sheet, the roller, or the like may sometimes cause the sheet to slip.
If conveyance efficiency decreases due to the slip, the ADF fails to convey a sheet at predetermined timing, and this may result in a sheet jam.
To cope with such problems, in Japanese Patent No. 4235124, there has been disclosed the invention of an image forming apparatus including a sensor for detecting delay in conveyance of a sheet on a conveying path; if an amount of delay exceeds a predetermined value, the image forming apparatus displays a message prompting replacement of a rotating member such as a roller.
However, in the invention of the image forming apparatus disclosed in Japanese Patent No. 4235124, by the time the delay in conveyance of the sheet is detected, abnormality in the rotating member on the conveying path has already arisen, and downtime of the image forming apparatus may occur.
The downtime is a time from when a function of the image forming apparatus, such as a copy function, becomes disabled and a user calls a maintenance agency for maintenance work until the function of the image forming apparatus becomes available to use again thanks to maintenance work. If a user calls for maintenance work after occurrence of a downtime of the image forming apparatus, the down time may lengthen.
So, early detection of abnormality in the rotating member enables the user to call the maintenance agency at an early stage. This makes it possible to shorten the down time. Furthermore, by adjusting a time required for the maintenance work to convenience of the user, downtime may be prevented from occurring during a time when the user uses the image forming apparatus.
Therefore, for the purpose of predicting the occurrence of abnormality in a conveying member, a threshold value used for detection of delay may sometimes be lowered. However, if a time from when an amount of delay exceeding the predetermined value is detected until a slip resulting in the occurrence of a sheet jam occurs is too short, it is not possible to achieve the purpose of predicting a sheet jam.